Visual Imagery Lecture Notes PDF

Visual Imagery In today’s lectures, we will discuss: What is Mental Imagery? What is Visual Imagery?...

Visual Imagery In today’s lectures, we will discuss: What is Mental Imagery? What is Visual Imagery? The Imagery Debate Spatial vs Propositional representations in the mind Imagery & Perception Imagery & Memory Imagery & the Brain KMF 1023 COGNITIVE PSYCHOLOGY Lecturer: Norehan Zulkiply FSKPM, Universiti Malaysia Sarawak What is imagery? Mental imagery: forming images in your mind even though the actual stimulus that you are The Imagery Debate: imagining is not present experiencing a sensory impression in the absence Spatial vs Propositional of a sensory input representations Visual imagery: “seeing” in the absence of a visual stimulus (eg. counting the number of windows in your home, describe your mother’s face.) Applies to other senses too, eg: smell, taste, touch Visual Imagery Visual Imagery Shepard & Metzler (1971)’s Results: experiment on Mental Rotation Linear relationship Participants were asked to look at the two pictures and decide quickly between reaction whether they represent two different time(RT) and angle of views of the same object OR two orientation different objects Showed that Measured the time taken to participants were rotate abstract objects rotating image of the RT for (b) > RT for (a) objects in their mind It took longer to compare 2 objects during the that are separated by a large angle, experiment then it took to compare 2 objects that are separated by a smaller angle Prove the existence of Mental Rotation 1  Visual Imagery Shepard & Metzler (1971)’s experiment on Mental Rotation was so influential Imagery & Perception – do they share the Demonstrated a parallel between imagery and same mechanism in the brain? perception Imagery is not vivid/long lasting BUT shares many We see an object moving through space when we properties with Perception see a real object rotating, and that we have Linear trend in rotation...suggests spatial similar experience of movement through space correspondence when we rotate an object in our mind The spatial experience for both imagery and perception match the layout of the actual SEE (perceive) object rotates & IMAGINE object stimulus. rotates Further support from Steven Kosslyn – image scanning experiment Participants create mental images and then scan Do they share the same mechanism? them in their minds Visual Imagery: Image Experimental evidence for image Scanning scanning Stephen Kosslyn (1980, 1994) To investigate the time it takes to Visual imagery is spatial in scan between two locations on a nature mental image (spatial = involving space)  a representation in which different parts of an image can be described as corresponding to specific locations in space It should take longer to find things within imagery that are further apart Experimental evidence for Experimental evidence for image scanning You are Here image scanning Participants are shown a map of an Results: island containing a The farther apart the two objects were, the greater hut, a tree, a rock, the reaction time a well, a lake, sand, and grass When people operate on mental images they appear to Learn the map of the go through a process analogous to actually operating island then imagine on a physical object the whole map Although they did not have the actual map in their Participants were then heads, they were going through a process similar to asked to mentally the physical operation travel between the various locations on the island and be the time it takes to scan between objects in a mental aware of about how image is a function of distance between the objects. long it took to move between the locations 2 Image scanning : Associated data Visual Imagery Linear relationship Support for visual imagery as a spatial between distance and representation: response time Mental rotation (remember mental Mental scanning rotation) Further support Is there another explanation to the that imagery is spatial in nature mental rotation and scanning data? The Imagery Debate Propositional nature of Imagery The imagery debate... Pylyshyn: Just because we experience imagery spatially,doesn’t mean the underlying representation Zenon Pylyshyn (1973): is spatial Proposed that imagery is related to Imagery has a propositional representation – in mechanisms associated with language which relationships can be represented by symbols. use words to represent objects and relationship between Imagery is propositional in nature objects instead of visual / spatial as suggested by eg. In (dog, bathtub) Kosslyn A spatial (depictive) representation of “in(dog, bathtub)” would look something like this... Propositional nature of Imagery Propositional nature of Imagery Spatial (depictive) Propositional Another eg.: Propositional representation Spatial (depictive) representation representation representation Door beneath In (dog, bathtub) window Has 6 tires; 3 on each side Tires are black and round Many researchers more agreed with the Kosslyn’s idea that visual imagery is spatial in nature 3  Comparing Imagery & Perception Size in the visual field: Relationship between viewing distance and the ability to perceive details – similar in perception and imagery Imagery & Perception > the size, the > detail available with visual imagery Perceiving a car from far away would only allow it to fill only a portion of your visual field; difficult to see details – but as you move closer, it fills more of your visual field and allow you see the details of the car Comparing Imagery & Perception Conclusion to Imagery & Perception Imagery & perception are closely Mental walk task: related Imagine walking Share some but not all mechanisms toward the ostrich Perception occurs automatically when we look at something but imagery needs to be estimate how far you are generated with some effort from the ostrich when you begin to experience Perception is stable but imagery is fragile overflow Harder to manipulate mental images than When the image fills your images that are created perceptually visual field Provide evidence that images are spatial Imagery & Memory Paivio’s - Dual-coding theory: Memory is served by 2 Imagery & Memory systems:  1. Verbal  2. Nonverbal Each handles different kinds of information, and that the two can communicate with. each other too. 4 Imagery & Memory Imagery & Memory Support for dual-coding theory. Concrete nouns create images that other Paivio’s experiment: Paired-associate learning task: words can “hang onto” Participants were presented with pair of words during learning such as “pen-honor”, “boat-hat”, “car-house” Eg “boat-hat” can create image of a boat During recall test later, they were presented with one of the then can hang image of the the hat on the words and asked to recall the word it had been paired with boat Results: Memory for concrete nouns (hotel, Paivio’s theory highlight role of imagery as a garden) which can cause us to create images is way of encoding material in memory much better than memory for abstract nouns (knowledge, honor, custom) which are less likely for Important: Memory is better if material is imagery to happen encoded in both the verbal (language) & In parallel with Conceptual Peg Hypothesis  nonverbal (visual) systems concrete nouns create images that other words can “hang onto”. Using imagery to improve 1. Visualizing interacting images memory enhances memory Pictures used by Wollen (1972) to study the role of creating 2 ways imagery can improve memory: bizarre images in memory, eg. “piano-cigar” 1. Visualizing interacting images enhances memory 2. Organizational effect of imagery enhances memory  Method of Loci  Pegword technique Visualizing interacting images 2. Organizational effect of imagery enhances memory enhances memory Results: “Method of Loci” Visualisation is most effective when A method of which things to be remembered images of objects are paired in an are placed at different locations in a mental interactive way image of a spatial layout. Memory is better for interacting images Pick a route that is familiar to you eg. the rooms in compared to non-interacting images your house. Pick 5-7 objects/events that you want to remember. Create an image representing each ( c)& (d) better remembered than (a) & (b) object/event and place each image at a location in the house so that they will be encountered in the correct Bizarreness had no effect order. Retrace the path in your mind to see if the (d ) was not better remembered than (c) image helps you to remember the objects/events. 5 Organizational effect of imagery Organizational effect of imagery enhances memory enhances memory “Pegword method” Eg. First item you need to associate imagery with concrete words remember is a dentist’s Eg. One-bun, two-shoe, three-tree, four-door, five-hive,six-sticks, seven-heaven, eight-gate, appointment nine-mine, ten-hen Imagine your teeth biting into a bun (one) (first Easy to remember order as created by rhyming them with the number item) Pair each object to be remembered with each Useful to identify objects to pegword by creating a vivid image of the be remembered based on object with the pegword the order on the list Imagery & the Brain Evidence from: ERP’s Brain Imaging Imagery & the Brain Imagery neurons Neuropsychological case studies Transcranial Magnetic Stimulation Imagery & the Brain Imagery & the Brain ERP’s (Event related potential) Brain Imaging studies Conducted experiment asking participants to read concrete nouns(can create images – like Confirmed that imagery creates activity truck and house) or abstract nouns (more in area V1, the primary visual receiving difficult to create images – like peace and area (occipital lobe) ethics) Area V1 is involved in imagery Results: Imagery response occurred in two areas that are associated with object perception in the brain occipital lobe especially area Visual receiving area (V1) temporal lobe 6 Imagery & the Brain Imagery & the Brain Neuropsychological case studies There is evidence that some neurons Case of patient M.G.S are category specific Had part of visual cortex removed as treatment for epilepsy Eg. responded to baseballs but not faces Task: Imagine walking towards a horse Before removal of visual cortex, she can get to within 15 Same neurons responded when feet of the horse in her imagination. After removal of visual cortex, the horse started to overflow imagining the baseball but not when at an imagined distance of about 35 feet. imagining faces (imagery neuron) Results: Removing part of the visual cortex reduces the size of her Imagery Neurons field of view, so the horse filled up when she was farther away. Area V1 in visual cortex is important for imagery Transcranial Magnetic Stimulation Summary (in new book pg. 282) Function of imagery Mental imagery - Mental representation of stimuli that are not physically present Function: To temporarily disrupt the functioning of a brain area (by applying a pulsating magnetic field to the skull using a stimulating coil) The imagery debate: Spatial vs Propositional representation During disruption, a participant’s behavior is tested (asked Kosslyn vs Pylyshn participants to carry out a perception task or an imagery task) If the behavior is disrupted, it is concluded that the deactivated Evidence for Spatial representation area of the brain is causing that behavior Results: visual cortex (V1) plays a causal role in both Perception Mental rotation- For every equal increment in amount of rotation, an equal increment in reaction and Imagery time is required Image scanning- the time it takes to scan between objects in a mental image is a function of the distance between the objects Summary Summary Imagery & Memory Imagery in the Brain Paivio’s Dual Coding theory The occipital lobe especially area V1 is  2 forms of encoding in memory (verbal and important for imagery nonverbal) There exists Imagery neurons in the brain- respond only to images of specific How imagery helps to organise memory objects  Interacting vs non interacting images  Method of Loci  Pegword method 7